Принята к печати статья в журнал Inorganic Chemistry

Gleb A. Silantyev, Oleg A. Filippov, Peter M. Tolstoy, Natalia V. Belkova, Lina M. Epstein, Klaus Weisz, Elena S. Shubina

"Hydrogen bonding and proton transfer to ruthenium hydride complex CpRuH(dppe): metal and hydride dichotomy"

Inorganic Chemistry2013


The combination of variable temperature (190-297 K) IR and NMR spectroscopy studies with quantum-chemical calculations at the DFT/B3PW91 and AIM level had the aim to determine the mechanism of proton transfer to CpRuH(dppe) (1, dppe = Ph2P(CH2)2PPh2) and the structures of intermediates. Dihydrogen bond (DHB) formation was established in the case of interaction with weak proton donors like CF3CH2OH. Low-temperature protonation (at about 200 K) by stronger proton donors leads via DHB complex to cationic non-classical complex [CpRu(η2-H2)(dppe)]+ (2). Thermodynamic parameters of DHB formation (for CF3CH2OH: deltaH° = -4.9 ± 0.2 kcal·mol-1, deltaS° = -17.8 ± 0.7 cal·mol-1·K-1) and proton transfer (for (CF3)2CHOH: deltaH°PT = -5.2 ± 0.3 kcal·mol-1, deltaS°PT = -23 ± 1 cal·mol-1·K-1) were determined. Above 240 K 2 transforms into trans-[CpRu(H)2(dppe)]+ (3) yielding a mixture of 2 and 3 in 1:2 ratio. Kinetic analysis and activation parameters for “[Ru(η2-H2)]+ → trans-[Ru(H)2]+” transformation indicate reversibility of this process in contrast to irreversible intramolecular isomerization of Cp* analogue. Calculations show that the driving force of this process is greater stability (by 1.5 kcal·mol-1 in deltaE scale) of the dihydride cation in comparison with the dihydrogen complex. The calculations of the potential energy profile indicate the low barrier for deprotonation of 2 suggesting that the formation of trans-[CpRu(H)2(dppe)]+ proceeds via deprotonation of [Ru(η2-H2)]+ to DHB complex, formation of hydrogen bond with Ru atom and subsequent proton transfer to the metal site.

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